Robot Blood?

InSPACE will explore a curious phenomenon: When some low-density MR fluids are exposed to rapidly alternating magnetic fields, their internal particles clump together. Over time they settle into a pattern of shapes that look a bit like fish viewed from the top of a tank. Such clumpy MR fluids don't stiffen as they should when magnetized.

The structure of particles in an MR fluid gradually changes when an alternating magnetic field is applied. The leftmost picture shows an MR fluid after 1 second of exposure to a fast-changing magnetic field. The suspended particles form a strong, fibrous network. The pictures to the right show the fluid after 3 minutes, 15 minutes and 1 hour of exposure. The particles have formed clumps that offer little structural support.

The fish tank pattern is fragile and takes about an hour to fully develop. It doesn't occur in MR fluids that are constantly mixed and agitated, as in a car's suspension, but it could prove troublesome in other situations.

The pull of gravity on Earth can distort the pattern - a frustration to scientists trying to study its underlying physics. That's why Gast and colleagues have sent their MR fluids to orbit. On the space station, astronauts can expose a weightless (freely-falling) fluid to magnetic pulses and record what happens.

"Astronauts are an integral part of our study," notes Lekan. They will reach into the Microgravity Science Glovebox, where the experiment is located, to align and focus cameras on a spot only 0.2 mm wide. If a fluid bubble gets in the way of the shot ... flick! they can remove it.

more A prototype MR washing machine

In early April 2003, ISS Science Officer Don Pettit conducted the first experiments with MR fluids inside the glovebox. His two-hour "run" marked beginning of the InSPACE investigation, which will likely continue off and on throughout the month.

Meanwhile, some companies are already forging ahead with new magnetorheological devices. Lord Corporation of North Carolina, for example, is designing an MR washing machine. Magnetic dampers inside the machine will decrease noise and vibration - and save energy. They're also studying MR technology for seat belts and airbags in cars. Because MR fluids can generate large forces quickly and flexibly, they could be used by automakers to adjust the arresting force of a seatbelt to the size and weight of a passenger.

Saving lives and silencing washing machines - and that's just the beginning. Not bad for a bunch of gray oily goop.